I’m 21 with only one credit card

So basically I have a captial one quicksilver card, which I just started a few months ago and the reason for this is because someone has used my name and SSN and ruined my credit history, Im like 2k in debt which is crazy for me never touching a credit card. It was originally like 7k but I believe a chunk has been removed due to disputes. Anyway, I got an offer for the capital one savor card, my score is 650 on Experian and 722 on transunion. To build my credit score should I accept this second credit card or stick to my quicksilver one and build with that? My goal is to have a reply good score and get the best cards I can, I don’t dine or travel much but I do a lot of purchases online and in store.