It is simple. The structure was that Israel was God's people. Then they became unfaithful and in Jer 31 a new covenant was given to where the structure would still be Israel but not of the flesh, but of the spirit.
We can't rely upon what Jesus said and not on what Paul said. Neither of them knew that the structure would be limited to 144,000. That was not revealed until Revelation.
Starting at Pentecost, the Israelites were anointed with holy spirit and adopted into the covenant, then in Acts 8 the Samaritans, then in Acts 10 the Gentiles. Then people in general whom God chose were anointed with holy spirit until the 144,000 were filled. This was filled around the mid 1990s.