Travel for 4 adults from Gatwick to Covent Garden

by "best way" do you mean cheapest, fastest, most private or easiest to use?

Do you want to actually arrive at Charing Cross station, or just generally in the Covent Garden area?

Thanks,looking for the fastest way in,to arrive near Charing cross.

National Rail says Thameslink train to Londonbridge station change to Southeastern train to Charing Cross. 50 to 60 minutes.
https://www.nationalrail.co.uk/

The quickest route is to take the train from Gatwick to London Bridge, then change and take the train from there to Charing Cross. It's a 40 minute journey if you don't have to wait too long for the first one.

Alternatively you could go to Victoria (normal train, not the Express) and then take the Underground (District line) to Embankment. That is just a couple of hundred metres along from Charing Cross and is perfect for hotels such as the Clermont. It's probably 45 minutes. Walking along from Embankment doesn't take much longer than walking through Charing Cross

I would just pick either of the above, based on which is pulling out of Gatwick as you get to the platform.