To answer some of your answerable questions:
is 2 weeks standard?
Yes. Offers usually have an expiration date. 2 weeks is very reasonable. Companies will sometimes push you to make a decision immediately or within 24 hours to prevent you from continuing to interview and potentially getting better offers.
Secondly, the school semester would not have even begun by then, which means I would not even have a chance to see what other companies are doing before making a choice. Is this normal?
This seems less normal to me. I don't have a ton of internship experience (either as an intern or hiring manager), however, asking you to make a decision 8-9 months in advance feels unusual to me.
As to the unanswerable question of "Should I take this job", there are lots of things to consider. It sounds like this is a good, respected company. You interned there and they immediately offered to have you intern again the following summer. They liked you. A lot.
Did you enjoy it? Would you want to work there again? Would you want to get hired there when you graduate?
If those things are all "Yes", strongly consider accepting their offer. There may be other opportunities available, but if you like the one you have, what are you hoping to gain by looking and maybe finding something better or maybe finding something much, much worse.
If any of those are "No", strongly consider declining their offer. They are a known quantity that you aren't super interested in. There are lots of other big tech companies. They will also likely desire your skills and pedigree. It may be worth keeping your options open.