User friendly software for math drawings

I’d look into Tikz, which is a package for LaTeX. It’s fairly intuitive if you’ve used LaTeX before and I think (based on your description) it’s good for what you’re going for.

Here’s a link to an Overleaf page describing some of its basic functionality:

There’s obviously more you can do with it (I recently used it/an extension of it to draw circuits for a Laplace transform paper I wrote), so you can do some more googling to find what you think you need out of it. Good luck!