First thing. Don't panic. The reason why you have a good credit score is so that when you need credit they approve it.
Check the dates to make sure that the application for newest credit card, and the creation of the other credit card match the dates you expect.
You mention two things:
JPMCB-Card Service: Opening a new account...
That is a new card. That does several things. Your credit utilization goes down, which is good. The second thing that is does is decrease the average age of your accounts, which is bad. Both of these are expected. This isn't a hard pull. This is a change to your credit history file.
CBNA-New credit inquiry: Applying for a new line of credit...
That is a new application. New applications always hurt your score. Again this is expected.
Over time both of these aspects will diminish. You score will go back what is normal for you. It might even get better.
What you experienced is why the advice is don't apply for a new card just before you need to apply for a car loan or mortgage. Doing so makes the lender very concerned. They see activity and they know it is recent and they wonder if you be able to afford the loan they were about to approve.
The fact your score went down is expected. Congratulations. Your great credit history allowed you to get two cards in the past few months.
I applied for the Chase card (JPMCB), and was approved months ago.. why would they all of a sudden make an inquiry?
They didn't. The wording you cite for Chase states "opening a new account", not an inquiry. Inquiries happen when you apply, immediately; accounts take a month or two to show up, typically with your first statement. Your new Chase account has started reporting.
If you have a thin file (not many cards/loans), a new account will likely drop a key element of your score - the average age of accounts - significantly. You're focused on inquiries, but they're not the likely culprit here.
Cancelling the card will not improve things (as the new account will be on your report for years, even when closed). Time is the fix here. You've got two new cards; now's the time to let them age gracefully for 6-12 months.
Do not cancel those cards
Let me explain
Applying for a credit card can hurt your credit score a little. According to FICO, a hard inquiry - when a card issuer pulls your credit after you apply - can lower your score. However, the impact is temporary. Hard pull stays on your credit report for two years, but their credit score effects wear off after one year.
A credit score impact of a single card application can be small, too many of them in a short amount of time can add up to a significant loss.