Hard to quantify, but stuff like PrEP (a drug used to prevent HIV infection) has probably saved a staggering number of lives across the globe, same with the yearly influenza vaccines.

For a more personal one?

I'd say the innovations to bikes, which have been staggering since 2000. Downhill mountain bikes have had staggering changes that make them lighter, faster, stronger, and way more stable, and they look dramatically different to their 90s counterparts. Stuff like dropper posts, modern full suspension, tubeless tires, disc brakes, and massive cassettes make them incredible. You can roll over a cantaloupe-sized rock at 20mph and the bike will just take it without you being ejected over the bars.

Ebikes have totally changed the calculus in hilly cities, even in flat ones to some extent. Being able to effortlessly bike 45 miles and not be totally thrashed the next day is such a gamechanger, it's actually beyond belief. My car has been largely collecting dust because most trips day to day are under 45 miles. And it takes pennies to recharge vs $90 or so to refill the tank.

Bikes already help take tons of cars off the road worldwide, but ebikes could really help extend people's ranges, particularly if they would normally drive otherwise.