Keep getting rejected

I have been actively applying to companies for roles like Forward Deployed Engineer, DevRel and Applied AI engineer.

But I keep getting rejected in the application phase only. I understand that I may not have experience in that domain, but I'm pretty sure that I do have those skill sets required for the roles.

Wanted to understand, what is the majority reason for these rejections? Is it that someone got hired for that role behind the scenes or it's my no-experience in these domains or my resume doesn't highlight the the JD requirements.

YOE: ~ 3 yrs