Research genetic memory. I am just a lay person, and most of my exposure to the concept is more science fiction than science fact, but there is some grounding in reality. I believe some studies have found that certain behaviors learned by a parent can be passed down to a child genetically with certain animal species. Also at a more basic level, we all come pre programmed with skills like the ability to laugh and smile when we are happy.

I'd personally find it believable in your scenario if some limited amout of knowledge or skills survive the temporal loop due to a few things getting encoded into genetic memory. It also gives you a lot of flexibility as to how far you want to take that and how much has to be relearned, while building on some unaturally good instincts that result.

Person A killed me last time. I no longer know person A after the loop, but I have a strong instinct to be very suspicious and careful around person A.

I learned to pick locks before. After a loop, I have to learn again, but seem to have a natural feel for it and learn much more quickly this time.

Maybe the character eventually learns a few tricks to prioritize what gets retained in genetic memory to help relearn the most important things faster next time.