The burial mounds of our ancestors were constructed as a micro-cosmos. The buried ancestor dwelling inside the mound was placed sitting uprised on a high-seat or often laid down in a fetal position, faced towards east (where Sól - the sun rises). The entrance of the mound was also faced in the East Wards directon, symbolizing the re-birth itself out of the realm of death and into the light. Other graves were arranged with the skulls put inside a constructed birds nest, resembling eggs. Yes, the graves of our ancestors, in all their formats, tell a story of re-birth and re-incarnation.
In what our Norse ancestors called "the mound age" - they built this micro comsos with the burial chamber first - or especially in Scandinavia; placed a whole ship with the dead inside, and with all the belongings of the dead - with symbolic relics and items. On the ships they built the burial chamber itself. They mored the ship to a big stone. They tossed soil over and thus made a mound covering it all, and planted sacred trees on top of it.
This micro cosmos, our known world in miniature, is the same micro cosmos a fetus has in the womb of its mother. Mythological ships and their names and kennings all tell that the symbolism of these ships are in fact a micro cosmos - a womb - the same way Frey (the seed, the ancestor) has one, soft as silk but strong and durable as wood. The same way Loki (the adrenaline, the one setting things in motion) has one - hard - made of finger nails of men - when he sails towards the battles of Ragnarök (the new beginning, the actual birth/re-birth). Everyone who has experienced or seen a physical birth, will understand this symbolism very well. There is no need for further explanations.
The rope moring the ship and the dead to a big stone, is of course something one did at a practical level at sea and port - but, it was also done symbolically to "more" the dead to its ancestor and the ancestral soil. It was done symbolically to connect the dead to the ancestors - the same way the fetus is connected to its ancestors via the umbilical cord in nature before the physical birth.
In many, if not most, of the graves (complete chambers on ships, or ship formations) we find a sacrfied horse. Sacrified dogs were also common (well, wolfs - symbolically - representing the female side of re-production). We know from our mythology that horses are totem animals, and they are symbols of the meta-physical. They are vessels of the spirits - like Sleipnír - the eight legged (eternity) horse, sliding from realm to realm, from life to death and to life again, owned by Óðinn - your accumulated honorable ancestors. Our Norwegian fairy tales tell litterally of ancestors in the shape of horses - that the main character has to free from their spellbounds by being slain. The fetus in the womb, the dead in the fetal position, in the micro cosmos - are connected to such a vessel of the spirit. They are connected to their Fylgja (translated as afterbirth and follower in Norse). They are connected to their "old King" and the tree of life. If you are one of those that have experienced a physical birth - you would recognize this symbolism as well. The midwives in modern hospitals still call the placenta the tree of life. That is not a coincidence.
So, when all the scholars come to the conclution that the pagan graves are filled with items that the dead themselves wanted physically for a heavenly afterlife - you know that this is nonsense.
"The shirt of the dead has no pockets"
- Norwegian proverb