If people cross the channel to seek asylum they are often referred to as 'illegal' before their applications are processed.
If Trump has been recorded bragging about shooting people dead in the middle of the main road and still getting votes, and inciting revolt against the US govt, and asking a governor to find him some votes, he is often referred to as innocent until proved guilty.
To enter a country legally surely one presents a passport or ID to an immigration official at a border. Landing on a beach with no passport control is surely illegal. To my mind these people are illegal immigrants until proved otherwise