In one of the sidebars in GURPS Traveller, LKW explicitly stated as much. They wanted the aliens that the first Terran explorers find to be humans. To do this, they had to have something non-human spread primitive humanity out. Thus the need for the Ancients.kristof65 said:IMO, the biggest thing the Ancient's add to the game is the reason for humanity being spread all over that section of the galaxy ...
Without the Ancients, the Droynes are still pastoral TL<8 on their home planet. Grandfather invented the jump drive and uplifted the Droyne race. Without Grandfather to uplift the Droyne, there is no reason to expect them to have gained jump drive on their own. They were static. Grandfather was the stimulous to get them moving.
Without the Ancients, the Aslan are probably dead. It was the "discovery" of jump drive that allowed the Tlaukhu to survive, and without which it would have failed. It is established canon that the Aslan discovered jump drive because of a crashed Solomani ship. Then again, maybe not, as it would only take one Terran mistake to create a similar occurance. Who knows? But the Aslan survived because of "found" technology. Who knows if they would "find" the technology in a timely enough manner without the setting created by the Ancients.
Without the Ancients, the Vargr would of course not exist. Neither would any of the vast array of human races that were created by both the Ancients and by other humans. This isn't necessarily a net loss, as a whole new set of altered humans would likely result from advances in Terran technology.
Without the Ancients, it is not even a sure thing that humans would have survived long on the interstellar scene. It was their competition with, and wars against, the vast Vilani Empire that forced the Terrans into anything that remotely resembled a cohesive force. Without the presence of a common enemy, there is no reason to believe that the Terrans would not have reduced themselves to petty internal wars with catastrophic. We can be optimistic, of course, but there is in our current track record that would indicate its chances.
Without the Ancients, a large portion of Charted Space would be dominated by two powerful enemies, both of whose reach would eventually close enough to Terra to influence it. At that point, Terra's survival would depend on which found it first. I am, of course, talking about the K'kree and the Hivers. They would be the dominant empires of Charted Space.