Unfortunately, you have no choice But to work with this "defend at their spawn" crap till about 1.9k-2k
Fortunately heros who are good at zoning like junkrat can help your teamates live through it. Since spawn is basically a choke, keep a safe distance and go nuts. If they die, make sure u dont. Play your best play smart.
High output low skill heros can carry u to 2k if u are worth your salt. after that.. u will need to work on higher skill cap heros.
Try heros like Junkrat, mei, symm, winston.. they dont take alot of skill but u can do alot of work at lower tiers easily.. carry yourself out of elo hell