The Constitution explicitly says that "representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State..." (14th Amendment, section 2). Nothing in there about only counting citizens. The very next sentence talks about "citizens of the United States" being eligible to vote for Congress, so they knew the difference between "citizens" and "persons" and clearly intended to have non-citizens counted for reapportionment even though they can't vote.
And more to this: In the only clarifying cases on this issue ever adjudicated by the Supreme Court, the Court made it clear that the definition of US persons in Amendment XIV was intended only to include those "subject to its jurisdiction," which does not include illegals, Indians, or the children of foriegn nationals not intending to remain in the United States.
Of course they did. They included slaves and women.
But that doesn’t mean they meant to include foreigners.
Perhaps they did, but both in the original and in the 14th, it’s not clear-cut.