What's the name of this cartoon style?

The style could be named after its instigating minimalistic 'Flat design', or is simply called 'flat illustration', but it could also very well be there's no (official) terminology for this specific form of graphic design (yet).

'Flat design' has become very popular in the last 7 years or so. I think a major influence on this style becoming more common was the increasing popularity of tablets: as they are controlled through touch screens and have relatively large screens, they required a new way of navigating, and large and easy to see tiles were an obvious choice.
As dynamic, coloured tiles organized into grids were used, the need for hierarchical vertical navigation diminished, and so did the need for extensive use of highlights, drop shadows, and other depth simulating effects and 'skeuomorphic' design elements (iOS 7 indeed embraced this need for a renewed design, but I think a better example of these changes is Microsoft Windows 8, which design is called 'Metro' (a.k.a. 'Modern UI').

Around five years ago, the need for a more intuitive design became apparent, and innovations on flat design were grouped under the name 'Flat design 2.0' (or 'semi-flat' or 'almost flat design') (for more background information, see here, here, and here).
These innovations include a reintroduction of shadows and other 3-dimensional effects.

As common user interfaces change, graphic design and illustration have to 'evolve' along with them (arguably because users like their digital experiences to be unified), and this is why flat graphics and illustrations have become very popular.

Good design necessitates the need for specific changes within these styles to be compatible with and complement the other, so improvements are made constantly, and these influence naturally occurring preferences (like in all art styles).
The current trend in illustration seems to favour somewhat naive depictions, as in the image you have posted. The increasing presence of humans (of different skin tones) could be a reaction to current political events, or simply to the idea that (web) design ought to be all-inclusive.