There were not 11 billion people at that time as farming methods could not support them (we can hardly support 6 billion people now) There is no fossil or bone evidence to suggest anyone has lived to be 900 years old. Women only produce enough ovum to sustain fertility until their 40's and 50's. Whether or not they lived for 900 years they could not have had multitudes of children.
Indeed. Who knows if it was actually 900
years, literally? There could have easily been some kind of translation error. Try replacing 900 "years" with 900 "months"; that might seem more reasonable, at least nowadays.
