According to the 2015 mobile game "Star Wars: Uprising", humanity's homeworld is Coruscant. Since this game was made after May 2014 and with the approval of the Lucasfilm Story Group, this information can be considered fully canonical, albeit I rather suspect that retconning it (e.g. they actually had a different homeworld which people are largely unaware of) would be trivially easy.
Coruscant tends to be the favoured planet in the Legends EU canon.
Taungs are warriors first and foremost, having battled the native Human nations for control of Coruscant before being driven off and
forced to flee to the Outer Rim world of Roon, where they remain for
millennia until the legendary Mandalore the First leads them to
conquer another world. Taungs rename both the world and themselves in
his honor, becoming the Mandalorians.
Star Wars: Galaxy at War - RPG Sourcebook
Essential Guide to Planets and Moons
Marvel Star Wars #84 - Seoul Searching (n.b. Notron is another name for Coruscant according to the Star Wars: Essential Atlas)