Brutus is relevant in early Roman history primarily because he led the Roman revolt against the Etruscans, which played a significant role in the establishment of the Roman Republic. Lucius Junius Brutus is often credited with expelling the last Etruscan king, Tarquin the Proud, and helping to establish a system of governance that replaced the monarchy with elected officials. This event marked a significant turning point in Roman history, as it laid the foundations for the republican system that would influence Rome for centuries.
The other statements provided, such as setting fire to Rome, presiding over territorial expansion, or being the first Emperor of Rome, are not accurate or associated with Brutus.