Not true. Most of the Texicans were legal immigrants. They had agreements with the Mexican government. The Mexican government changed, and began to renig on the agreements, giving ample legal reason for the Texican revolution.
These only rebelled when the government of Mexico, i.e. Santa Anna, decided to forgo the Constitution and the protections it offered Mexican citizens.
Mr. Austin was in jail in Mexico City after going there to try to resolve the issues peaceully, and did not return, or approve of the revolution until after it had actually begun.
Many of the imigrants into Texas in the 1820's and early 30's specifically checked to see what the Mexican constitution said. Also, another Mexican state, South of the Rio Grande, rebelled also. Both they and Texas rebelled, not to achieve independence, but to restore the Constitution. -- The flag over the Alamo was the Mexican flag w/ the date 1824, the year the Mexican Constitution was established. The move for independence followed the Alamo.
Don't know just who you mean by "We". Some Texians were illegals, most were not. Immigrants were addmitted under the Mexican Constitution, which was patterned after the US Constitution and guaranteed certain fundamental rights. Santa Ana overthrew that Constitution, or at least that's the way the Texians and Tejanos saw it. Many of those fighting for Texas/Tejas were Tejanos rather than recent immigrants from Europe or the United States, although the later made up the majority. The town of Seguin is named after one such man, Juan Seguin. About the same time Santa Ana was trying to put down a similar rebellion on the Yucatan Peninsuala. His commander there, a relative of some sort IIRC, made the mistake of trying to attack Campeche, which since early Spanish colonial days, had been guarded by two substantial forts, and the city itself was walled, although I don't know just how much of the wall was standing in the mid 1830s. The Forts were well armed with cannon, which the local militia used to shoot the cr*p out of the Federal Mexican Army. The area was independent for a time, with protection from Mexican Navy predation for it's merchant vessels provided by the Texas Navy under an agreement between the two former provinces. Sadly, the Yucatan suffered from infighting and was shortly returned to Mexico, a fate which likely would have befallen Texas, if not for it becoming a state of the United States.
That's not true ---the Mexican government was newly independent from Spain and Texas was part of the nothern territory it obtained from Spain. Mexico couldn't convince Mexicans to move to Texas, it was having trouble controlling Indians and so invited the Anglos to move to Texas and help develop the territory. The Anglos and Hispanics of Texas got along well enough but the Mexican government was a big mess and so Texas broke free from it.