Tafsir and Chains of Narration

S 25:33 And they do not bring you a similitude but we have brought you the truth and the best tafsir.

The Quran is the Best Tafsir?

The 'best tafsir', supposedly quran, BROUGHT to some unnamed guy, has chains of narration supposedly going back to someone calling himself 'Muhammad'.

The 'best hadith', supposedly quran, has chains of narration supposedly going back to someone calling himself 'Muhammad'.

The Best Hadith

Non-quranic ahadith have chains of narration supposedly going back to someone calling himself 'Muhammad'.

What chains of narration going back to the founder of Islam do the opinions proffered in tafasir considered better than the 'best tafsir' have?

As Muslims are very keen on their chains of narration and are quick to call a hadith 'daif' if one of the transmitters is thought to be somewhat unreliable, but the chain of narration's supposedly going back to the founder of Islam, shouldn't Muslims be bothered about so-called scholars giving their own explanations and quoting those of others that are not recorded as going back to Allah's boss?

What might qualify a mufassir, or even Allah's boss, to interpret what only Allah can interpret?

None Knows Its Interpretation But Allah