Allah calls Ka'bah as BAITI (My House). This enforces the thought that Ka'bah is the Source for humankind to regain their long lost unity. People can own any houses but not BAITI, Ka'bah, so that it remains accessible to all mankind and people can rally around the Ideology it represents.
Read the following verses intently to understand the significance.
22:26 Behold! We pointed the site of the Sacred House, Ka’bah, to Abraham, saying, “Associate none with Me, and keep (BAITI) My House clean of human dogmas for those whose Divine Ideology of Monotheism will revolve around this Center for all mankind. Train the visitors to stand up for truth, and bow to and fully submit before Divine Commands.” [2:125, 2:197, 3:95-97, 22:28-29]
22:27 “And announce to mankind the duty of Pilgrimage. They will come to you on foot, and on every kind of fast mount, coming from every far away point on earth.”
22:28 So that they might see with their own eyes and experience what benefits the Divine System holds for them (in addition to uniting them in the common bond of humanity). And they shall commemorate God’s Name collectively during the specified days of Hajj; and over the livestock He has bestowed upon them. Then host one another with the livestock (to make the Congregation self-sufficient in the food resources). Eat and feed the distressed poor (regardless of whether they are in the congregation or not).
[An important note: Most people think that non-Muslims are forbidden from coming to Makkah and Madinah but this belief is contrary to the Qur’an. The idolaters are forbidden only to ‘ya’mur’ or administer the Masjid for obvious ideological reasons. (9:17-18, 3:97). In fact, they must be allowed to come and witness the benefits of the unity of mankind. (22:27-28)]
22:29 As they host one another, they shall consult to clean out their societies of moral vices, and design ways to fulfill their obligations. Then they shall walk around the Ancient House in their resolve.
22:30 Thus it is the purpose of Hajj. Whoever will honor these Divine directives and limitations, it will be good for him in the Sight of his Sustainer. The livestock here is lawful food for you except for those already prohibited. You shall avoid confounding truth with falsehood, idol worship in any form, and abstain from bearing false witness. Avoid all things that bring your progress to a standstill. [2:173, 5:3, 6:145, 16:115. Rijs, Awthan, Zoor encompass all the stated meanings.]
Please study QXP. It will answer most of your questions.