“It’s pretty impressive that over 2000 years only 9-10 differences have shown up.”
Amen.
That we had lost the mesorah from Sinai regarding the spellings in the Torah was known by Chazal. See Kiddushin 30a. The real question is why people who know better say otherwise, such as in the introduction to the Artscroll Chumash.
Nevertheless the fact that there are 9-10 differences today, and more spelling differences with the manuscripts that existed in the time of Chazal and the Rishonim, not to mention the Qumran manuscripts, must not be used as an excuse to be nihilistic and to question the validity — or the Divinity — of the Torah. Not a single one of the spelling discrepancies has any halachic consequence. Nor do the apparent post-Mosaic additions such as the last 7 verses that describe Moshe Rabbeinu’s death, or a few other such examples cited by Ibn Ezra and a few other classic commentators. Every one of the small number of variant spellings, and every one of the few apparent post-Mosaic additions, needs to be treated as the word of our Creator. As in other areas of human inquiry, the simplest explanation here is the best, which is that a few spelling errors slipped in thanks to copying that was 99.9% perfect but not 100% perfect. Only HaShem is perfect and He commanded *us* to write sifrei torah; he didn’t miraculously create them.