Hi! Thank you so much for your feedback and your kind offer!
To answer your question, yes, the knight character is a free asset from the Itch.io website. Regarding your offer to redesign it, thank you, but there's no need for that. I think I might leave this project as it is and start working on a completely new game idea soon!
I really appreciate your notes about the barrels and the jump physics; they are very helpful for my future projects.
Thanks again for your amazing support, and see you around