This is also true. It doesn't change the fact that the Spaniards did manage to force the bridges during the Noche Triste.
Forced is a bit of a strong word, given that the causeway was initially unguarded, and the Aztecs were not anticipating an escape, due to Cortez sending envoys regarding a ceasefire. The 20,000 Aztecs weren't lined up in formation at the causeways; they were often in their homes and haphazardly ran to chase to the Spainards.
Pre-modern night retreats were often successful, regardless of the parity of the combatants. Washington was able to escape unscathed from Brooklyn Heights, for instance, and his army was woefully inferior to the British, as the battles right before his retreat can attest to.
Note that when the Aztecs were prepared at the Fall of Tenochtitlan, the Spanish had significant issues forcing the causeways in the initial phase, when most of their allies had not yet arrived and the defenders were not weakened by food/water shortages.
It's still instructive that Spanish casualties ranged in the dozens. The battle clearly shows that the Mesoamerican style of warfare was incapable of resisting a cavalry charge. And almost the exact same scenario would have played out if you took, say, a Roman legion and its cavalry complement.
Otumba was a confluence of a lot of factors that benefitted cavalry. The Aztecs were looking for prisoners instead of kills, were overconfident due to their numerical superiority and their success during
La Noche Triste, had never encountered cavalry in battle before, and met the Spainards on an open plain. When Pedro de Alvarado made a cavalry charge across a causeway at Tenochtitlan, he and 8 others were wounded, and 5 men were dragged off and later sacrificed.
A similar story with the Inca, where after initial battles where cavalry proved decisive, Incan remnants were able to neutralize cavalry in subsequent battles through the use of missiles and traps with technologies that are available to the Aztecs.
And I will add that the Spanish conquest of the Triple Alliance is not an isolated event. The conquests of the Inca and the rest of Mesoamerica demonstrate that, while specific events were important, in the Longue durée, the military advanatages enjoyed by the Eurasians were significant enough that symetrical military opposition to them was not actually feazible for a force relying on a purely American system of warfare.
The Inca were decimated by disease and had just wrapped up a civil war. I would argue that Cajarmaca was closer to a massacre than a battle, given that the Incans were largely unarmed bar ceremonial weapons and expecting a diplomatic meeting. After Cajarmaca, Atahualpa ordered his forces to stand down and the two succesive Sapa Inca after Atahualpa under mobilized their soldiers to aid the Spanish, causing mass confusion among the soldiery elsewhere that resulted in the Spanish victories from late 1533 to 1535. After that, the Spanish employed plenty of native auxiliaries.
As for the conquest of the Yucatan and Central America, those regions were far less centralized and populous, and the Spanish continued to use plenty of native auxiliaries. Something to note is that many of the states that allied with the Spanish received many benefits and retained a lot of their autonomy. Tlaxaca for instance retained much of their territory, were granted
hidalgo status, and even led settler-colonization efforts in Chichimeca. As a result, they continued to send forces to aid Spanish conquistadors, not only out of obligation, but also to conduct their own form of expansion.
I do agree that the Europeans had a military advantage in a 1:1 fight, but that was offset by their ability to project force across the Atlantic in the 16th century.
Yes, native allies were invaluable, but it's not like the idea of making allies from the opressed peoples of an empire was a novel idea that the Spanish had an exclusive claim on. We can see the exact same idea pop up pretty much everywhere, as far back as the first wars between the Sumerian city-states.
That's true, although I will note that a brand new power arriving/emerging upsets the diplomatic status quo and allows for the new power to leverage alliances to achieve dominance. It's a similar reason as to how previous "backwaters" can suddenly become great powers seemingly out of nowhere, like the Rashidun Caliphate, the Vikings, and various steppe nomads. However, diplomatic maneuvering isn't the same as military superiority.