Socially behind

Not in a sense that idk how to be around people but more like about knowing basic stuffs. When i m with my friends aside from talking about other people or girls or movies/series or what we ve been up to, i usually don t understand much and don t have much to say cause of that. So I m just out there listening, asking questions all the time. Kinda makes me feel like ass to always be in that position, like i m just uninteresting and when i do try to talk about something new or about myself, usually nobody really asks questions in return. I m definetly fun to be around, i know how to joke pretty easily and make others laugh, be entertaining but that s it. I m just not interesting as a person. So I ve been trying to learn new things and read but like i just wounder how everyone else knows these things and i don t. Feels like i m behind but idk where to start cause the things they talk about can be anything so I m like where tf did learn about this or that and why am i the only guy lost.
I know they don t think highly of me, just cool and funny to be with, so I feel like a fucking clown that s never taken seriously. I m just dumb and ignorant to them, which i get considering everything i just said. This has also been a problem with my relatioships with women, as i can make them laugh all day and flirt easily but when it comes to serious topics i never know enough to converse about it in detail, i just give my two cents or ask questions.
I m tired of being an uninteresting person with only a fun personality, just there to entertain but to never be taken seriously.
Any advice on where to begin ?