alt Hacker NewsThere is more certainty about the resilience of lattice cryptography to classical attack than there was about Curve25519's resilience when it was introduced. Lattice schemes weren't invented as PQC schemes; they were invented as faster classical schemes. In the 1990s, there was a live debate about whether lattices might be the successor to RSA, not curves.
With the caveat (for other commenters) that "lattices" means several things that were not viewed with a unified lens in the 90s and 2000s, the main lattice scheme of interest now (LWE) actually was introduced in a quite literal sense as a PQC scheme.
In the early 2000s, Oded Regev was looking into quantum computing algorithms for various worst-case lattice problems. He was able to create an efficient quantum algorithm for a particular one (SIVP_\gamma), if he could only obtain an efficient quantum algorithm for a certain novel/simple problem (the learning with errors problem). He was unable to do this, so instead framed his result as a reduction from SIVP_\gamma to LWE, and additionally showed how one can build cryptography from LWE. This is essentially the contents of his 2005 LWE paper, for which he later got the Godel prize.
So in a quite literal sense, LWE is the byproduct of a failed search for a quantum algorithm for SIVP_\gamma, and was therefore "post-quantum from the start". Regev mentions this as his initial motivation for looking into LWE on page 4 of his LWE survey
https://cims.nyu.edu/~regev/papers/lwesurvey.pdf