Can a human read a QR code?

No — a human can't read a QR code's content by eye in any practical sense. The data is encoded as binary modules arranged by placement rules, interleaved with error-correction blocks and XOR-ed with one of eight mask patterns to balance the pattern visually. Decoding one manually means undoing the mask, re-ordering interleaved codewords and computing Reed–Solomon corrections — hobbyists have done it on paper as a puzzle, but it takes hours for even a tiny code.

What you can spot by eye: the version (bigger grid = more data), and thanks to error correction, that a code with a logo covering part of it can still work (up to about 30% damage with the highest correction level).

Moral: since nobody can eyeball a code's destination, always check the URL preview before tapping.