When it comes to credits, can we put any additional credits on the jam page as well?
For example, if I have 10 plugins, do I need to credit each one individually in game / on the itch page?
I'm not sure I understand the question exactly. Just in general you should credit every person you used materials from. You don't have to credit each individual plugin, but you do need to credit each coder/artist/musician/etc. (So if you have 10 plugins, made by 3 different plugin creators, you should credit those 3 people).