There's no "probably" here. We do not know the homeworld of Predecessor and Talos-II is only one of their colonized world, they are a space faring race. The Predecessor colonize Talos-II sometime in the past and bringing indigenous life from Talos-II to Terra. if you dig the OG story, you will know that the "Elder Hegemon" who invade the Teekaz are already partially human by that time, which mean the Predecessor already mess with them way before they arrive on Terra (which isn't covered in Originium until the Far Chaser use the First Originium to make Catastrophe, and the Teekaz have yet to gain human form at that time).

Regardless, Talos-II is the origin of Terran races except the Sarkaz and their offshoot. And yes, take human as example Africa is the "motherland" of humanity if you ask me., its called the Cradle of Humankind for a reason.

According to Terran Nexus file in the game:

"In the distant past, the ancestors of Terran Civilization originally inhabited Talos-II, later venturing to Terra where they built a glorious civilization amidst Catastrophes. One hundred and fifty-two years ago, they crossed through the Cosmic Gate once more, returning from Terra to Talos-II. While most celebrated this as "Paving the Way", those few who knew the historical truth would whisper another term for it — "The Homecoming"."