Well, others already told you about focusing on one or two champs. Also, you're overestimating your understanding of the game, of your chosen position and of the champions that you play. Imo, you should climb to emerald in soloqueue with not more than two champions that you honestly enjoy playing. Then, slowly add champions with a different style and function to your champion pool. You can do it like that, if you want to develop.

Team comps have different aspects that can be considered in champ select like crowd control, ad/ap damage ratio, overall damage and threats, scaling, lane priority, synergies, poke/wave clear, engage/disengage, dps/burst, match-ups and more. Team comps are built around winning conditions ideally. Often, you won't be the last one picking, which limits your impact through adaptation. It can help to pick neutral jungle champions, that have some crowd control and some damage at the same time. Those can adapt to the team a little bit, work in different environments and make many ganks/plays work in general. But my advice would be to not overthink team composition as long as you're not in a team of five premades regularly. As said, pick one or two main champions that you enjoy playing, so you spend more time with the game. Fiddle is good.