The topic of the blessings of Abraham makes me think of Galatians 3. Paul wrote, "Now the promises were spoken to Abraham and to his seed. He does not say, 'And to seeds,' as referring to many, but rather to one, 'And to your seed,' that is, Christ" (Gal. 3:16, NASB). So the "seed" of Abraham is singular. And that one-and-only seed is Christ.
Fascinatingly, a few verses later Paul declares, "As many of you as have been baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise" (Gal. 3:27-29). There is only one "seed" of Abraham, but by being baptized into Christ, we become members of that single seed.
This was foreshadowed all the way back in the promises to Abraham - this singular seed would be like the stars of the heavens, sand by the seashore, and dust of the earth. He would be one individual, yet composed of many parts.