If you are thin, but out of shape, lifting will give you very fast results, in terms of shape (looks not fitness though of course it will help with fitness). Because when it’s not obscured by fat, the muscle shows very quickly. But also you are probably judging yourself more harshly than others are.

And really - if you are thin, lift weights. I am kinda slender middle aged lady and even without the benefit of testosterone guys have, lifting weights quickly gives me shape through the arms and shoulders that really improves my look. I do it now more to keep my bone mass but it’s certainly the quickest path to looking shapely.