Alleles are a pair of genes located on the chromosomes
No. Alleles are variants of a gene that exist within a population. Try again.
The genes that cause RH negative
Have only been recently added to the human genome
No, Rhesus-negativity is caused by loss-of-function mutations, meaning that such people do not express the Rhesus antigen, resulting in it becoming targetted by the adaptive immune system (after the first exposure).
Also, rabbits are also Rhesus-negative, as seen in the original experiment.
And their human embryo will have a tail
This is universal, not limited to a particular blood group.
An RH negative mother will reject
A baby from a RH positive father
Only if she had already been pregnant with a Rhesus-positive child, or more rarely if she gets exposed to Rhesus-positive blood through blood transfusion. Also, if the father is heterozygous, each child only has a 50% chance to be rhesus-positive (and remember, the reaction requires both this and a previous pregnancy to be Rhesus-positive).
The blood will build up antibodies
And attack the alien substance
Wait, aren’t you claiming that it’s Rhesus-negatives who are the alien hybrids?