This project overall is excellent and IMO deserves wider recognition. I almost want to create a new game just to use it :)

To answers your questions:
1) A few words of description (maybe onmouseover titles?) in UI would help. For example, I was initially confused by the fact that buttons on animation preview pages do not change their images when I pick different hero (i.e. I thought that buttons themselves were preview while in fact you must press them to change preview animation).

2) Export options are just fine. Since target audience is programmers, it is relatively easy to convert between spritesheet and list-of-sprites, so IMO you could even get away with fewer options. If you still want to add more, one idea is to export each animation as a single animated png (or gif).

3) As I said, UI is a little bit confusing at first, but honestly it is quite a minor hurdle compared to the value of the project.

4) The only real improvement I see for this project is GIVE ME MORE :) In particular, I think melee attacks are obvious missing element

5) They are nice as "inspiration generators", basically a more consistent version of generative AI. As a dev, I would also be interested in exporting palettes as e.g. JSON to facilitate programmatic recoloring. Also, some 'effect applied' palettes like e.g. burning, frozen, etc. might be nice

Anyone else have thoughts or Feedback? I’ve added additional tooltips, edited the order of animations and adjusted the export info.

Steady progress, rated it.
Would you consider adding a sword/staff melee attack animation? I think this is currently the only element lacking.
Also, maybe help text should include a few hints on proper integration of animations (for example, expected x-offset in pixels per frame of walking/running)?

@AlSoKnown, here's a draft "attack/melee item" animation that can apply to sword/staff/wand.

Is this along the lines of what you mean?  A caveat is I'm staying in 16x24 frame, like all other anims.