1. Humans have general intelligence. 2. Human brains use biological neurons. 3. Human biological neurons give rise to human general intelligence. 4. Artificial neural networks (ANNs) are similar to human brains. 5. Therefore an ANN could give rise to artificial general intelligence.
Many people are objecting to #4 here. However in writing this out, I think #3 is suspect as well: many animals who do not have general intelligence have biologically identical neurons, and although they have clear structural differences with humans, we don’t know how that leads to general intelligence.
We could also criticize #1 as well, since human brains are pretty bad at certain things like memorization or calculation. Therefore if we built an ANN with only human capabilities it should also have those weaknesses.