Personally, I don't think Lewis is anywhere close to Senna in being that much faster than his peers. Not because he's not necessarily naturally that much faster but mainly because with the nature of the cars, the telemetry, everything that is modern F1, there isn't as much of a lap time differentiator between the very good and great drivers as there used to be. The brakes are so good and braking distances so short that a mere two hundredth gain in braking distance in one corner is what separates the best brakers from the decent guys.
There is so much telemetry available that driver performance converges. So the only real opportunity to see a driver's natural talent shine is when we get very difficult conditions, wet races etc. We've always known Lewis' strengths from the moment he entered F1. His natural speed, his ability in the wet, his race craft - overtaking and defence. But there were weaknesses such as trying too hard, not managing the tyres or the race, a lot of negativity on the radio when a race wasn't going his way, impatience, mistakes under pressure. But experience, age, maturity has smoothed most of that out. He still gets a bit stroppy when things don't pan out exactly as he expects, but he doesn't lose his sh*t completely like before and doesn't make a lot of mistakes even when under pressure.
He's achieved so much, he's so confident in his abilities, barely anything phases him anymore. Even in 2012, his turnaround year after his disaster 2011 season, though his performance in 2012 was superb he still lost his marbles when Jenson out qualified him in Spa. In contrast, in the last few seasons including this season, he shrugs off being out qualified by his team mate. In China he was struggling all weekend, he was perplexed about his pace, but there was no panic even while his team mate was lighting up the timesheets while he was floundering away almost a second a lap slower for most of the race weekend until it mattered in qualifying.
So when you take a driver of his natural speed, add bucket loads of experience, including the experience of having had some high calibre drivers as team mates, iron out the above mentioned weaknesses, while adding in the calmness and confidence, then it's no surprise that you get a pretty complete driver who is extremely difficult to beat over a season.