In the first few Friday The 13th movies, Jason's backstory is a bit vague. When Pamela Voorhees is revealed as the killer in the first movie, she explains that her son drowned because camp counselors weren't paying attention. That story becomes complicated when Jason shows up as a fully grown man in Part II, so is he a zombie, or did he just never die in the first place?
If you go with the idea that Jason didn't die as a kid, then it really doesn't make sense that at no point over the following 20+ years would he seek out his mother. Some fans believe that not only did Jason never drown, but he was actually raised by Pamela after all. The idea is that Pamela raised Jason and was extremely protective of him after the accident, growing increasingly resentful of the counselors for almost letting him die. When new counselors attempted to reopen Camp Crystal Lake, she was unable to control her anger and went on a killing spree. After witnessing his mom's death, Jason felt he must avenge her and protect their home from more dumb teenagers, and that's where the rest of the series comes in.
It's either that, or Jason lived in the woods for two decades by himself and never once came in contact with Pamela, which would be pretty dumb.