New answers tagged style-identification
This effect is referred to as "low-poly." The name comes from 3D models with a low number of polygons. Search for low poly and you will find a lot of examples, tutorials, etc. as this style has been somewhat in vogue lately.
Pictogram or icon would be the most likely term used for these types of figures. See Wikipedia's article for more information. Of graphic design interest would be the image of the swimming pictogram signage from the 1972 Munich Olympics in that article.
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