2d side scroller simple flying chase AI? - are there any tutorials? documents?


So I have a side scrolling platform type project. I want to have enemies either flying around preset paths and others chasing the player.
Are there any documents or tutorials that might give me an idea as to where to start with this?
Literally every tutorial I find on AI requires a nav mesh. Which is no good for me as I don’t want the enemies on the floor. The flying AI tutorials I found are really complex using thrust parameters etc.
I’m just trying to create a really simple arcade type game, so preset paths or literally a sprite floating towards the player will do.
Maybe I’m looking for the wrong thing but in the last hour I have not seen anything that looks even remotely useful to me.
(imagine your typical side scroller shooter where enemies come in waves but then there are some that will try and chase you…that’s all i want)

any help will be greatly appreciated.