The linguist survey isn’t a great source since it’s significantly biased towards languages that are easy for *English speakers* to learn, which is quite different from languages that are easy for children to learn as a first language. A lot of the languages that are at the beginning of the list are Romance and Germanic languages, and other languages that are morphosyntactically similar to English (eg. most of the “1” languages don’t have noun classes, like you mentioned).
The linguist survey isn’t a great source since it’s significantly biased towards languages that are easy for *English speakers* to learn, which is quite different from languages that are easy for children to learn as a first language. A lot of the languages that are at the beginning of the list are Romance and Germanic languages, and other languages that are morphosyntactically similar to English (eg. most of the “1” languages don’t have noun classes, like you mentioned).
I think that’s a fair criticism.