Sure plutonium-239 with half life of 24,000 is not particularly radioactive, neptunium-237 has half live of more than 2 million years, both are extremely dangerous to humans for multiples of that time.
Half live is not directly related to the level of damage gamma decay can do to you. Elements are perfectly capable of emitting hazardous amounts of radiation for thousands and millions of years time.
We cannot barely build a phone to last 3 years, The incentive to not create problems for future generations is simply not there. If it was, we would doing a lot more for pollution and plastics and the mass extinction event we are currently causing.
I don't believe our track record as a species warrants any trust on the ability to build containment to last thousands of years.