I had no idea a Buddhist would sound like that!
Q: who would've killed Cain?
A: everyone (per Cain's fear) no one (per G-d's provision)
Ya know, I have never crunched the #'s the way you did. It is rare to encounter someone who digs up a nook or cranny I have not considered! Yet your 2 listed options here are a textbook illustration of a false dilemma.
W/o doing the requisite fact checking let's just assume you're right, that Cain was 90 years older than Abel. (This doesn't at all seem right to me, considering) That leaves 70 years between them, for A & E to have an untold # of children, who then in turn have an untold # of children. Crunch those #'s and you could conceivably have some pretty large clans wielding torches and pitchforks
Buddhists have an affinity of saying "having something is nothing, having nothing is having something".
Actually, I did not say such thing. I assume that Abel was a year younger. He could also be Cain's twin and be a minute younger since the Bible didn't exclude that possibility.
Descendants Adam's age
Adam's age, given. 130
Knew his wife and Seth was born 129
Jabal 15
Lamech 15
Methusael 15
Mehujael 15
Irad 15
Enoch 15
Time Cain fled 39
Cain's possible age at the time of killing = (time fled - Adam's age) is 24
Abel's age = (Cain -1) is 23
Abel's first possible offsrping = (Abel's age at time of death minus generation gap) is 8
Generation 15
Age that Jabal, et al, procreate is 14
Assuming Adam's age when Cain was born 15
Since the Bible didn't say it, Adam could be
1 year old when Cain was born but I'm trying
to be consistent with the generation break down
I assume that Cain was the first son. When A begat X in the Bible, it's always assume that X was the first son, unless there's an explicit mention of a sibling.
So, working backward, these patriarchs of Cain's descendants must have been 14 years old when they procreated. That's 14 years + 1 year of pregancy equals 14 year generation gap. The 15 year generation gap is a miracle in itself if that was true. That meant that all 7 first borns were male and they all survived. If the generation gap is more than 15 year, Abel could not have an offspring.
Even with all these miracles, Cain would be 24 years old, and Abel's first possible offspring would be around 8 years old. I don't know how many 24 years old would be so afraid of primary school age kids.
And while yet another possibility has been mentioned, I'll just point out you seem to be operating under the assumption that for anything to be excluded from the Bible, there needs to be a good reason. The opposite is true: exclusion is the default, and inclusion requires something of special significance. (Specifically as it relates to the unfolding of the Gospel as a means of joining man to G-d)
Let's see if I understand this quote. In other words, if the Bible didn't say it didn't happen, it could happen?
There are only a few reasons why things were not mentioned in the Bible.
1) It didn't happen
2) It happened but it was immaterial
In Genesis, the deaths of Adam, Seth, Cain's descendants were mentioned but not Cain, nor Eve. It's a possiblity then that Cain and Eve are still living? Technically, they could die a day before Judgement Day. Or maybe the Bible didn't mention their deaths because it was deemed immaterial?