Re: mythmaking
A few things we can all agree on.
1. Vyasa composed MBh. It was narrated by others AFTER the deaths of all main characters.
2. Harivamsa, whether or not omposed by Vyasa, was done after Krishna's death.
3. SB is a much later text.
Therefore, Krishna had no part in the myth making done via HV and SB.
Let's take MBh. More facts we can agree on.
4. Panchali was the one without a childhood, with a magical birth.
Pandavas had magical tales, too.
Both of those events had purposes. The men's being throne of Hastinapuri. Hers being eventual empress. Vyasa was involved in both myths.
5. Krishna's magical origin is not present in MBh. Even if someone did include it, there would be no point at this point in time because Krishna had no official role.
6. Krishna's weapons were named so by Varuna. Not by Krishna. In fact, Krishna and Arjuna were reluctant even to take part in the whole Khandava thing and agreed after persuasion by "grandfather."
7. Panchali was present in Khandava.
8. Indra's aim in Khandava was to kill Krishna.
Speculation: If Krishna actually died, how difficult would it have been to transfer what he did to the female Krishna? More mythmaking.
9. Until now, Krishna had no myth in Mbh
10. Shishupala vadh happened. Bheeshma, whether mockery or not, said Krishna was god.
Krishna didn't respond to it.
Here, it was BHEESHMA acting against Vyasa's mythmaking.
11. Dice hall happened. Panchali myth was shattered in public. Vyasa's attempt at portraying her as a magical woman was gone.
12. Vyasa wanted war. He said so to Yudhishtira.
13. Narada and Vyasa worked in conjunction.
14. Exile ended and Krishna magic started.
Extrapolation: with Panchali myth destroyed, Vyasa needed another myth for people to follow. Pandavas couldn't be it because their myth was also gone. Krishna was it.
15. After all main characters died, Vajra and Janmejaya took up the stories for their political purposes.