1. that's not proof at all
2. The one "factor" you didn't include was age:
Minato died at approx 24, right? And 13 years later when Jiraiya met naruto, Jiraiya was approx 55 (seeing as the 3rd died approx 70) so, by the time naruto was 13, minato would've been 38.
55-37= 18. I highly doubt Jiraiya and Tsunade had a child at 18. There's that and the fact that its been 621 chapters and not the slightest mention of this. Do you think Minato would be completly oblivious to this? He did make Jiraiya Naruto's godfather (you're not going to be a godfather if you're a grandfather).
did you forget Jiraiya said this:
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