I haven't played Minecraft since 2016, and I remember why. For some reason my hotbar items were being selected automatically (from 1-9 the selections would continue until it reached the end of the hotbar then start again with 1) and when I tried to select them using the number keys, the selected item would just be the start of the new repetition of selections. This has not changed, I have tried to try a new world, delete and re-download the app, and restarted my computer. Nothing works.
No, my arrow key is not stuck.