It
sounds like you're trying to land your first job in "tech" (as much as design can be considered tech)?
I remember applying for literally hundreds of jobs and getting little or no response when I was finishing up my studies (so, a little under 20 years ago). As you describe, it's quite depressing to feel "wow this job sounds great, it's just what I'm looking for", you spend the time writing the application, re-reading and tweaking bits, you submit it, and get this giddy feeling of "what it will be like".... and then nothing. Zip. Nada.
It's unfortunate, but I would say
@casperes1996 makes a good, if understated point with his last word.
Luck; right time/right place have definitely played a significant role in my career, and thus, my life. But "who you know" is also an important factor we like to tell ourselves doesn't matter. It absolutely does. Not for every single job, obviously. But honestly, "luck" and "knowing someone" have had a significant role in easily the first 7 or 8 years of my career.
What country are you in? Are you applying to agency type companies, or direct to software companies? Have you considered freelancing part time to build out a more extensive portfolio?
Edit: typo.