Many Jewish traditions were laws of the old testament, many of which were for the kingdom of Israel specifically, others were for the temple, but since both of those no longer exist, the laws no longer apply to us. The kingdom of Israel was dissolved and the temple was destroyed, so those laws meant for the kingdom and the temple don't matter anymore. However many traditions were traditions of men, which Jesus condemns in Matthew 15, which makes it VERY clear he did not obey nor believe them. Secondly the laws of the old testament were fulfilled in Jesus, because he was the only one able to stay 100% obedient to the Father. Because he fulfilled the law, some laws we don't have to follow today, such as not eatish shellfish and not to wear garments of mixed threads. But some of the laws still apply because 1.they are basic morality and 2. They can be found again in the new testament. An example of this would be the sin of Homosexuality both condemned in leviticus and Roman's 1:26-27. Also, just to clarify, Jesus didn't believe everything in Judaism from the time. Like I said before, some traditions were created by men, not by Jesus, who is God incarnate as a man.