Mexican allowed to own guns legally in Mexico.

You’re correct. The rights that Canadians have to possess weapons are not constitutional rights, they are statutory.

Similarly, the right to drive a motor vehicle is not a constitutional right, it is statutory.

The right to possess cannabis is not constitutional, it is statutory.

The right to abortion is not constitutional, it is... well, there is no law in Canada that prohibits it.

The estimated total number of guns (both licit and illicit) held by civilians in Canada is

2017: 12,708,0001
2011: 8,619,3282 3 4
2010: 8,383,265
2009: 8,205,454
2008: 8,044,572
2005: 9,950,0005

https://www.gunpolicy.org/firearms/region/canada