ויאמר אלהם אני נאסף אל עמי קברו אתי אל אבתי אל המערה אשר בשדה עפרון החתי ... (מט-כט)
Yaakov Avinu gave precise instructions to his children how to proceed with his kevura after his imminent petirah. But the phraseology used here is interesting. Why did he say "אני נאסף על עמי" - “I’ll be gathered unto my nation”? What nation? At this point it was only Avraham Avinu and Yitzchok Avinu up in שמים.
R’ Moshe Feinstein zt”l says the following pshat. There were other righteous people who had already passed away. On this world they weren’t referred to as עמי, the same nation as the Avos. But in the עולם האמת where everything is clear, their status rose to a degree that they could be in the vicinity of the patriarchs as well. Thus, עמי includes the likes of Noach, Mesushelach, Chanoch, among others of their ilk.
Perhaps we can say another two thoughts that the Zaida (Baal Machsheves Halev zt”l) would no doubt agree with, if he did not actually say it. Granted there were only two Avos already in שמים but the אמהות were there too. Additionally, Yaakov would finally be reunited with his nshei chayil, Leah and Rochel. His wives, with whom he built such a beautiful familial edifice, were to him, literally, his "עמי" because they bore, raised, and built his "עם" of Yisroel.
And lastly, as the Zaida was wont to say at every simcha, our ancestors come down from on high to rejoice in and partake of our joyous events. And if, lo aleinu, there is a tzara in the mishpacha, a terrible “klop” for the family, we can count on them to intercede on our behalf, pleading for us by the kisei hakavod, the Heavenly Throne, so that we can emerge relatively unscathed. They are our melitzei yosher. Yaakov Avinu was telling his children, “Fear not that I am taking leave of you. I am being ‘gathered’ into you. I will be able to be there for you when needed.” Hence, the posuk aptly states that Yaakov said, "אני נאסף אל עמי", to my dear children and the entire nation. זכותם יגן עלינו, ולכל ישראל