Zippers have not yet been invented. Do keep that in mind. If there are any obvious zippers, this will be a source of wonderment. People were a lot more sharp eyed than you think back then, so they aren't going to miss that. Hoodies come in many different styles--some have zippers in the front, some are pullovers. The ones on pants might not be noticed but any front and center would be. EDIT: If you want a year on these they were introduced in 1893 at the Chicago Wold Fair, but they weren't produced commercially on a widespread basis until 1917, and even then they were only on boots and used to seal tobacco pouches. It wasn't until the 1930s that they began to be used on clothes, and that was mainly pants.
Snaps! A letterman's jacket features snaps. I don't know if you realize this but...snaps were not patented for at least another hundred years. While they have been intermittently used in history, in this time and place, it is pretty likely that in Salem they have never seen one. EDIT: The Chinese invented these way back in 210 BC, but they weren't commonly used, nor was the usage widespread. In Europe it wasn't until about the 1830s and 40s that they began to appear on theatrical costumes for quick changes, and then the usage moved to gloves. These early snaps were not reliable and tended to rust, and therefore were not all that popular. In the late 1800s and early 1900s the design was improved and began appearing on work clothes mainly, and on cowboy style clothing as well. In 1690s Salem they would not exist.
Lycra/nylon/stretch Any material with stretch to it is a goshdarn modern MIRACLE. Women were really, really good at eyeing fabric and qualities at this time. While your leggings and crop top girl might be branded as a slut, a kind woman that finds her would want to dress her immediately, knowing that she would be hurt otherwise. Then she would question her manner of dress for certain. Next, she'd be wanting a closer look at the fabrics. Actually, she might even offer clothing of hers to borrow in exchange just for a closer look at those leggings. Seriously! EDIT: Most stretch materials are a product of the 1900s, and the most usable are invented/widespread after 1950.
Blue Jeans So, the first use of the words blue jeans are like in 1790. But it's possible that blue work fabric might have been around for longer than that. Certainly, the thickness and type of fabric is one that your Salem natives might recognize as work pants. EDIT: The indigo industry has been working to undercut the woad industry in Europe for about 200 years. There was a ban on using it for quite some time that's lifted in the 1600s. During the 1600s the major producer of it in the Americas was Spain, not England. England was just getting into the business and it wasn't until the 1740s that it was grown in South Carolina by the French. In the 1700s it was big business, but in 1690, in an American colony established by the English, it wasn't as common as you might think--blue was produced mainly by woad, not by the distinctive indigo. Workers in Europe used similar material (mostly dyed brown or dark), but for a long time indigo was considered a luxury dye. Workers in Italy and Spain were more likely to use a blue jean type material. The late 1600s and early 1700s is precisely when there was this shift of it being more common--but in an American British established colony in 1690, the indigo blue jean material is odd.
Shoes You have forgotten shoes. Let me just say that if anyone is wearing sneakers...people will be mesmerized. Rubber has not been invented. Basically, everything about a sneaker is the result of an industrial age. The rivets, metal, plastic, rubber, colors, everything about them is wildly exotic and beyond the current tech of the day.
Socks Yep. depending on the type of sock, yes, your socks are astounding. If they have stretch, they are a miracle. Color, pattern, and everything else should be taken into account. Machined socks are...quite incredible. There's only one seam in the toe, and sometimes there isn't even that depending on how they are made. The weave is sometimes terribly fine and some socks are even a little fuzzier on the inside vs. the outside, even if they are thin. EDIT: Do some research on socks of the day, and stocking styles. Socks during this time were much higher, partially using the knee to keep them up. Decide on the exact style and type (because there's tremendous variation) and compare that to what was fashionable and available during this time. Any elastic stretch material, which is common in today's socks would be a big deal. Keep in mind that what's common in the 1700s and 1800s is not at all what they would have in 1690--machine works and the industrial age in Europe radically changed the world of socks and everything else very quickly. The Puritans favored wool socks. Using stays, ties and other things to keep socks up was common. Some socks had a built in string you would tie to keep them in place. They liked over-the-knee socks best, and would use the buckle or ties, aka garters, on their pants leg to keep their socks from slipping.
Details, details & Class You've painted a general picture of what they are wearing, but it's the details that will also matter. Are there any neon colors included in anything? Is there red? And if so how bright/dark? (Contrary to popular beliefs, Puritans did wear color, it was just fairly muted in tone.) Do the leggings end in lace? Lots of leggings have a lace band at the end or decorative detail--lace was outlawed for certain classes. Just saying leggings or just saying a t-shirt doesn't cut it. Anything with words, as one commenters pointed out--something like the Nike phrase "Just Do It!" would be very, very odd to these folks. The jeans, if they are ripped, if they are light blue or stone washed, or distinctive dark indigo -- these are details that will have an impact.
The recently lifted Sumptuary laws in England are a specific point of contention for Puritans. Sumptuary laws told certain classes what they were and were not allowed to wear. See, just before this, in the Renaissance a lot of fabrics and colors became available to the lower classes and to upstart merchants. It upended society, because prior to the Renaissance you could tell who was a quality person by what they wore, at a glance. So, laws were put in place to prevent people of certain professions from wearing certain things which, though they might be able to afford them, implied a higher class status. By the mid 1600s a lot of these were finally repealed, as they didn't work much anyway. But your Puritans don't think the way the rest of Europe did. Order, status, calling, all those mattered to Puritans. So while Europe was taking Sumptuary laws off the books in the 1620s, and getting more and more elaborate in dress, us Americans were getting stricter about what we allowed or not, and outlawing slashed sleeves. By 1690, courts in America were finally a bit more relaxed about actually prosecuting a lower class lady who wore a silk kerchief (though I think she was still arrested, just not tried).
The person you'd want to meet is someone such as Hannah Lyman...By 1690 she'd be a middle-aged or old woman...
IN 1676, HANNAH LYMAN WAS in trouble. She was among three dozen or so young women who had been summoned to court: They had flouted the laws of the colony of Connecticut by wearing silken hoods. Among these “overdressed” women, Lyman was, apparently, the most rebellious and strong-willed. She appeared in court wearing the very silk hood that she had been indicted for donning.
The sneakers will mark you as wealthy, but the jeans will mark you as workers. You could be from a far land with different customs, but you can bet there will be questions. Lots and lots of questions and people will pay close attention to your answers as well. Your folk are wearing a mix of class indicators, which means that people will immediately want to categorize them. During this time in Europe there were people who dressed beyond their status, however, the ones who most commonly mixed high and low in a bizarre way were often pirates. Saying that you are from Europe and that this is the new fashion might work though, because Americans really expected all kinds of bizarre fashions, changing very quickly from their perspective, as they are cut off from European centers of fashion.