So there’s according to Wikipedia 12 theories on why humans became bipedal, I remember there being more.
Anyways here’s a nice explanation for reasons to give your species human-like bipedalism:
The problem you’re gonna run in to is that a lot of these problems we might have evolved towards bipedalism to fix are just things primates sorta suck at but other animals have better solutions for, like defense or travel, or they’re things that require a ton of specialized primate abilities to make into a good solution (like we were good at reaching for branches. Which may work for koalas but not sheep).
The one thing I could see working is introducing a very deadly predator in the food chain that’s proportionally more intimidated by large-sized creatures. It is a cheap way to make yourself appear significantly bigger.
Also based on that picture your animal has fingers, low facial prognathism, a butt, ability to use tools, non-rhiperian nose, and maybe a chin and maybe permanently enlarged breasts which are all pretty unusual physical traits it’ll take a lot more working to evolve if you wanna use them.