the age diffrence between friends

sometimes i forget that im not an 11 year old anymore. im mean im not old, im turing 16 in like 2 weeks, but its still weird when i see that someone sends me a friend request or just wants so talk to me irl and i ask how old they are that they are like 17, 18 or older, and when i say that im still 15 or almost 16 they whould just not care? like i still have in my head that friends have to be around the same age. like mabye a 1 year age gap but not more. and now people older than me jsut dont care about that? like wdym i have friends that are almost 18 or a few that are like 24 or 25. AND WE CAN JUST HAVE NORMAL CONFERSATIONS AND RELATE TO EACHOTHER!? like damn. 

all my life i whould just be friends with classmates (so people around the same age) and now im going to a diffrent school and my classmates chould be like 10 years older than me? it just doesnt make sence in my head. like im still in my mid teens and im friends with a young adult? YOU ALREADY PAY TAXES AND SHIT? 

and the thing is, some people see me as the "old friend" like my youngest friend is 12. did i just adopt a kid? like fr i have a lot of friends and we just have like a family tree. like my friend and i are the parents but we got a divorce and now the 12 year old has a bonus dad which is my friends boy friend (who i think just turned 18)? and then my other friends a like aunts and uncles. and we just keep on going we have like 3 7th graders in our "care"

and dont get me started on online friends. like wdym you just spend your time chating with me and u dont care about that im younger? you dont see me as some weird little kid but just as a normal mature person?

 i still dont get that sometimes  but its fun to have so many diffrent friends