Well it is actually 蒸気船, スティーム ボート Willie, I don't know when it was made. The first ディズニー Princess movie was Snow White but not the first ディズニー movie. And wasn't Fantasia made before Snow White too?
yes, Snow White is first full-length ディズニー movie but if あなた mean first The Walt ディズニー Company's アニメーション so I think that it is "Osward the Lucky Rabbit"
if あなた watch the movie 塔の上のラプンツェル and wait until the very end, there is a countdown of the ディズニー 映画 from the 50th one (tangled) to the first one (snow white)