When people register with a dating agency or site, they cannot expect to like everyone or to be liked by everyone, so I don't think that there is any point worrying about that sort of thing
As for age, this is your life, so it is for you to decide what age feels appropriate ~ not your friends. I am guessing that a number of members are older because, until then, they feel that they have plenty of time.
You are right that online dating seems to be popular, but if you do
decide to meet up with someone, please be very careful! Try to have some friends nearby and to be in a public area, etc, etc.
Do you belong to any clubs, etc?
Sports, amateur dramatics, book clubs, etc, etc?
Perhaps you need to get out to places where you will meet people.
It sounds as if you have quite a few friends ~ where and how did you meet them?
Remember that 24 is still very young and that you have plenty of time to meet your Mr Right.