For the riding you seem to be describing, you likely want either a lightweight cross-country hard tail mountain bike or wide-tire capable rigid gravel/adventure bike (like Salsa Fargo or Kona Sutra). Large volume tires will make a big difference relative to your current bike and might be enough "suspension" for you. If you need a bit more, something like a Lauf fork is inbetween a rigid bike and a standard MTB suspension fork. But as others have mentioned, before you commit to a drop bar setup, try out some of the various flat bar options. They can make a big difference in how much control you have on those bumpy downhills.