Why is the covenant between God and the Israelites important?

The covenant set Israel apart from the other nations. They were (still are) God's chosen people. They enjoyed privileges as God's people. God said He would bless them if they obeyed but they did not obey.

But now there is a new covenant/testament:

Heb 9:13 For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean, sanctifies for the purifying of the flesh,

Heb 9:14 how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?

Heb 9:15 And for this reason He is the Mediator of the new covenant, by means of death, for the redemption of the transgressions under the first covenant, that those who are called may receive the promise of the eternal inheritance.