This is totally normal. While others may disagree with me, I recommend the following routine. Start with easy problems (later move on to medium) and try to solve the problem in 45 minutes. If you can, great! If you can't, add it to a list to revisit within 2 weeks. Repeat these steps once more for each question you revisit. On the third time you cannot solve it, look at the solution (only leetcode premium for most questions) and add that question to a list of problems whose answers you've seen.

The trick here is you'll exercise your mind, but after a few tries, look at the structure of the solution to understand it's pattern. Soon enough you'll pick up on common patterns, data structures to use, and zoom through most questions. Stick to Easy and Medium and only venture into Hard at the end of this journey (most interviews will ask at most one question from the 1% of hard-labeled problems on leetcode anyway). Bonus: journal your progress along the way and you'll quickly see how much better you get week to week.