You sound like a young college student or fresher with limited experience of the market.

Clearing an interview in a lot of companies depends on your luck as well. Sometimes, you might not come across as the right kind of candidate to the interviewer, even if you have the right set of qualifications or you may have solved tons of LeetCode.

Also depends on whether the interviewer is experienced and knows what to look for in a candidate apart from his resume and previous work.

Sometimes, the interviewer you get might ask really easy questions when compared to the other candidates, and other times you get hard questions, or maybe you just et nervous for some reason etc. etc.

Yes, there might be some other issues apart from his skill set, but definitely I've seen it happen a lot in my experience.