[jerzeygymwolf]

When I was a Tibetan Buddhist practitioner I remember someone asking a lama this same question - and his reply was almost identical to the answers in the above quote. He mentioned animals and beings from other planets.

yes, a very imaginative reply, by the lama. it seems clear by the sutta what is rare is the arising of Buddhas and taking a sincere interest in realising the special teaching of the Buddhas, namely, the Four Noble Truths. but discursively imagining this teaching to be about literal rebirth seems not to take a rare & sincere interest in realising the Four Noble Truths, i.e., extinguishing craving

if the question is asked: "Is realising the Four Noble Truths rare?", the obvious affirmative answer to this question makes complete sense

it appears literal rebirth is not present in that Sutta. it appears literal 'rebirth' is being inferred, as explained in AN 2.23 & AN 2.25