iMovie won't open iPhone videos!?

So, I have an iPhone 14+ and a 2020 iMac running Sonama and mistakenly thought it would be easy to edit my vidoes as 2 apple items are bound to be compatible right?! Wrong.

I've never used iMovie before, but I cannot get it to open the files. I've airdropped them to the mac, and it says:

iMovie cannot open files in the “QuickTime movie” format.

I did a quick google and tried opening the files in QuickTime and exporting them as h.264 files like it said... still won't work.

All I wanted to do was turn a load of wedding clips into a montage music video :(

Help please x