Whether the first reasoning entity is an individual organism or a group of organisms is completely irrelevant to the original point. If one were to grant that there was in fact a "first reasoning group" rather than a "first reasoning being" the original argument would remain intact.
Reasoning could very well have originally been an emergent property of a group of beings.
The animal kingdom is full of examples of groups being more intelligent than individuals, including in human animals as of today.
It’s entirely possible that reasoning emerged as a property of a group before it emerged in any individual first.