Going off @Bálint Budavölgyi's comment, I think the answer might be:
The Deathly Hallows, from Harry Potter
My reasoning is:
As Hint 1 says, the numbers in each list are not in order, so we must reorder them first.
The first line can be reordered as 1, 3, 6, 10, 15...; this has already been solved and verified as the start of the sequence of triangular numbers.
The second line can be reordered as 3, 1, 4, 1, 5...; this has already been solved and verified as the first digits of pi, the circle constant.
The third line (now updated) can be reordered as 0.5, 1.5, 3, 5, 7.5...; this sequence is the same as the first, but halved. (1/2, 3/2, 6/2, 10/2, 15/2...) This is why Hint 3 suggests that two of the sequences are similar.
Hint 4 suggests that the third sequence could also be 2, 0.5, 0.5, 1.5, 2.5. This can be reordered as 1.5, 0.5, 2, 0.5, 2.5...;, which is the same as the second sequence but halved.
These sequences clue towards:
the triangle, the circle, and then dividing one or both of those shapes in half.
Combining and overlapping these images gives the symbol for the Deathly Hallows, a collection of powerful artifacts in the Harry Potter universe said to have been created by Death.
"According to legend, he who possesses these three artefacts would become the Master of Death," which would explain why we can't kill Tim.
(In reference to Hint 2, the three aspects of the image each represent one of the artefacts. Specifically, the triangle represents the Cloak of Invisibility; the circle represents the Resurrection Stone; and the line that divides the image in half represents the Elder Wand.)