Listen, you're 16. If you get friendzoned, just bail. Life is too short to hang around women that you're in love with who couldn't care less about you. A girl saying "i just want to be friends" means 1 of 2 things. Either a) she's simply too spineless to say "I'm not interested in you, at all" or b) she wants to string you along because she likes having you for emotional support. Either of these is really bad.
I really really wish someone had told me this when I was your age. I spent my entire adolescence being friendzoned and being a doormat. A girl who friendzoned me when i was 15, who I spend the following 10 years being in love with until I finally stopped talking to her, recently found me on linkedin and sent me a long message about how much she regretted the way she treated me and how she loves me and how every guy has treated me like shit. We started talking again, then we started talking for like an hour or 2 every night, sending pics back and forth, the whole nine yards. Then she took a train almost a thousand miles to come visit me. Every time I tried to kiss her, she backed away. Every time I tried to put my arm around her, she wormed away. Every time I tried to hold her hand, she moved away.
Turns out she was actually still married to a guy who went crazy and ended up becoming homeless, and she was just using me for emotional support so she could feel loved again. (I thought she had been divorced already).
Biggest mistake of my life responding to her message on linked in. The whole thing taught me that once you get friendzoned, you're never getting out, and you will always get used. After she left, I deleted my OKC and tinder accounts and I decided that every time I think about how I wish I had a girlfriend, I'm moving $5 to a savings account. After one year of being single, I'll have enough for a vacation or a new guitar, or a PS4 and a bunch of games, or whatever. I'm all about me now. I will never again let a woman use me and manipulate me because of her fucked up life situation.
My advice is treat this girl like radioactive waste: Act like going anywhere near her is the end of your life, because it is. There are 3 billion women. Find another one.