A:  I believe the term "Jewish Holidays" is more appropriate, since they were given as a part of God's covenant with the nation of Israel in particular and have never applied to the world at large. Even rabbinic Judaism does not expect or seek for righteous non-Jews to keep these holy days. When non-Jews came into early church, no such rules were placed upon them. (See Acts 15:28-29) There are no new rules in the New Covenant (New Testament) regarding the Holy Days unless it would be the following:

 

"Don't let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day." (Colossians 2:16)

Because

"God made you alive with the Messiah. He forgave us our sins, having canceled the written code, with its regulations. . ." (Col 2:13b, 14a, see also Hebrews 8:13)

"…we have been released from the law so that we serve in the new way of the Spirit, and not in the old way of the written code." (Romans 7:6)
Some people may try to tell you that Gentile believers are free from the law, but that the old rules still apply for Jewish believers. However, the New Covenant Scriptures are emphatic that there is to be no distinction:

"Here there is no Greek or Jew, circumcised or uncircumcised, . . . but the Messiah is all, and is in all." Col. 3:11 (see also Romans 10:12, Eph 2:15,16, Galatians 6:15, Galatians 5:6, Galatians 3:28)

How does tradition fit in?

Some believers find new meaning in the old traditions, once they see them in the light of Yeshua. Others seem to need to make a clean break. In any event:

"One man considers one day more sacred than another; another man considers every day alike. Each one should be fully convinced in his own mind. (Romans 14:5)
"Therefore let us stop passing judgment on one another." (Romans 14:13)

"So whatever you believe about these things keep between yourself and God." (Romans 14:22)

In short, don't let anyone make you feel like you're sinning if you don't observe the holy days, and don't pressure anyone else to do so. On the other hand, if it useful to you and you understand that it is not something God requires of you, continue without guilt and without looking down on those who do otherwise. That is what I see in Scripture.
(Also, not all of the Holidays celebrated by the Jewish people today are mentioned in the Bible at all. Some are of later origin).