connection time LHR to Naples

Presumably the airline is offering you a couple of options – one connection looks like it may be kind of tight, and the other looks like it’s pretty long. 10 people here will have 15 different opinions on the best choice.

But really… It would be easier to provide you more holistic advice if you shared the specific itineraries that you were looking at, including airlines flown.

American Airlines from Dallas.

1 hr 50 min connection to Naples via British Airways.
Arrive London at 0625. Depart for Naples 0815.

Did you book all of this together through British Airways or American (as they are partners) or separately? A few years ago, we had a tight LHR connection and BA told us that they wouldn't have booked it if they didn't think we could make it. This year, we had a nearly 4-hour LHR layover between arriving from the US on BA and then taking BA to Milan. That was doable but long.

If you can, try to book seats as far forward as you can afford. That will get you off quickly. Be prepared for a long walk and a train ride to another terminal. You will go through Security again. Make sure that you've got your liquids in order. They were very stringent about anything remotely resembling a liquid (like toothpaste) be in ONE baggie. What passed through US Security didn't cut it in LHR. Plan ahead and you'll be good.

BTW: Maybe it will be better this season with cancellations. I booked our flights in November for May 2022. However, during those months, the flights changed numerous times. Don't get too attached to them.

Checking the AA and BA sites, the shortest transfer I can find is 2hr 35m, on a single booking. ( random Apr 2023 dates)

Is the 1 hr 50m a DIY cobbled together two ticket journey?

You may find this useful... https://www.heathrow.com/connecting-flights