yes, you should have focused on short content but along with it you have to post long content with it
both short and long form videos have its advantages, shorts videos are a good idea if you have started a new channel and want to garner views, shorts have more power than the long form videos algo, and since youtube is competing with tiktok they are sending out daily billions of views for youtube shorts, so to get the intital pump to your channel shorts videos are a good idea, however the earnings are pretty low.
Shorts are a faster way to enter the algorithm and gain authority on your channel for a certain topic. So yes, you can use this as a better strategy to grow quickly.