What framework(s) to improve my web app? Currently using react.js

Currently I have just about my full web app built out in React using mostly just javascript and css.

While the functionality is fine, I feel like its really lacking a very fluid user interaction and experience.

Am I limiting myself by just using React and javascript?

For my backend im utilizing heroku and firestore.

For reference, my site is an AI GPT app where users can easily create there own assistants and chat with them.My project site

Ive been using react.js and just utilizing javascript and html. I’m fairly new to developing, but most videos I see the developers use jsx and typescript.

Any and all feedback is great and I have linked my site to see what it currently looks like too