I think Jet2 flights are earlier in the day because 'daytime flights' as opposed to arriving at your destination at midnight or setting off back at 4 am a la Ryanair is one of their selling points. It's not always like that, but a lot of their flights are.
Also a lot of them are 'out and back' in a day, which I expect is cheaper on crew because they don't have to accomodate them overseas. The crew's job for the day will be to fly to Malaga and back or similar.
I've had good package deals with them, nice hotels and often cheaper than booking separately. I also like the hands off approach from the reps. We had a couple of packages where the rep stood up on the coach to the hotels, gave her speel about weather, things to do in the area and how we all had her phone number if we needed any help, but didn't try to sell any excursions etc or force anyone to go to a welcome meeting, like the packages of old.
We had another Jet2holidays package that was actually a boutique hotel with private transfer to Gozo, and that was loads cheaper and easier than booking the Malta airport to ferry terminal, ferry crossing and second transfer ourselves, plus the onus was all on them if something went wrong with any part of it. If we had arranged our own transfers and missed a flight, it would have been our expense, not theirs to sort out.
Since the internet became widespread, there's no practical difference between what a package holiday and a 'book it yourself' holiday looks like. You can book a villa holiday or nice quiet hotel on a small island as a package, or you can book a huge AI resort in Benidorm all separately so statements like 'we're not package holiday people' are now meaningless.