What's the purpose of this picture shown at the beginning?

It seems to be a modern reproduction of a Shakespearean-era tapestry illustrating 5 scenes (acts) from the play.

Left-most appears to illustrate Dani Ardor being traumatized after her sister Terri kills herself and their parents by filling their home with carbon monoxide. The Death's head above is sprinkling down the fatal gas.¹

Next, Christian and Dani argue about a trip that Christian was planning to take with some male friends without telling Dani. In an attempt to patch things up, Christian reluctantly invites Dani to come along.¹

Christian and Dani (together with Christian's three male friend, Mark, Josh and Pelle) travel to Pelle's ancestral commune, the Hårga, in Hälsingland.¹

After arriving at the commune, the group are offered some psilocybin mushrooms, and under the influence of the drug, Dani has hallucinations of Terri. Tensions rise after the group witnesses an ättestupa where two commune elders attempt senicide by leaping from a clifftop.¹

The next day, Dani is coerced into taking more psychedelic drugs and participates in a maypole dancing competition. She wins and is crowned May Queen, an esteemed title in the cult. The cult gathers together, sacrifices none if its members and burns their own temple to the ground. The bear at the bottom of this scene makes an appearance later with Christian¹

Someone is illustrated as an observer high in the left-most tree taking notes and recording the events.

¹ _{Plot descriptions and paraphrases are taken from Midsommar (2019 film) - Plot}