Use Epigenetic Intelligence Instead of Learned Intelligence
While the mechanism by which epigenetics works is not very well understood, some studies have shown that simple animals like mice can pass on genetic traits based on personal experiences such as the Cherry Blossom Phobia experiment. In the case of mice, you do not need to naturally select for fear of certain smells for their children to inherit genes that make them afraid of the smell, you just need for the father to learn to fear that thing, and their sperm will modify itself to produce children with a higher sensitivity to that smell which leads to a phobia of the smell as the child matures.
If you were to take a species like mice, but with a far more complex epigenetic mechanism, then a parent could pass down hard-coded adaptations to their children of a level of complexity resembling intelligence. So, if a parent learns that fire keeps them warm, their children will be drawn to fire. If those children learn that friction creates heat, then the grandchildren might be compelled to rub sticks together to make fire. The more generations that benefit from fire, the more that lineage will experiment with and learn to use fire.
As these behaviors become more complex, hereditary occupations would become a given. The blacksmith's son would become a blacksmith because he is not smart enough to become anything else, but he has a ton of genetic imprints from previous generations that make him a good blacksmith and more importantly WANT to become a blacksmith and loath the idea of becoming anything else. He will be both emotionally and intellectually incapable of choosing another path.
While these beings might be able to experiment to a degree, such choices would mostly happen at the subconscious level out of necessity the same way a person might choose to use a sugar spoon to eat their dinner because all of the soup spoons are dirty. It does not feel like a choice, just the closest thing you can do to what you would have chosen anyway. If the experiment works, it imprints itself for the next generation to continue to use, if it causes a problem it imprints reinforcing the proper use of soup spoons for the next generation making them more likely to stop an wash a soup spoon before eating.
One reason this species would not perceive free will is because the obviousness of a person's heritage would be so resounding that their culture would find it incomprehensible for a person to outright defy their heritage. Even if a blacksmith mouse were to all of the sudden decide to become a singer, it would be such a strange occurrence that the typical reaction would be something along the lines of, "Oh, I didn't know you had an ancestor who was a singer, do you know who you get that from?" Everyone, including the mouse, would take for granted that some forgotten ancestor was a singer and that this forgotten person is the reason he made that "choice".
The other key here is that 95% of what you know you never actually learned yourself. That means it is far safer to rely on one's instincts than to actively try to experiment to learn things for yourself. So, people who do believe in choice over just doing what you feel compelled to do would be selectively less fit.
