I downloaded the release build without modifying (https://www.lwjgl.org/customize) I put all the classes in Eclipse. Some classes are not recognized
The codes that do not need these classes in error, work normally. As in https://www.lwjgl.org/guide
All the classes I put:
joml-1.10.1.jar
joml-1.10.1-javadoc.jar
joml-1.10.1-sources.jar
lwjgl.jar
lwjgl-assimp.jar
lwjgl-assimp-javadoc.jar
lwjgl-assimp-natives-windows.jar
lwjgl-assimp-sources.jar
lwjgl-bgfx.jar
lwjgl-bgfx-javadoc.jar
lwjgl-bgfx-natives-windows.jar
lwjgl-bgfx-sources.jar
lwjgl-cuda.jar
lwjgl-cuda-javadoc.jar
lwjgl-cuda-sources.jar
lwjgl-egl.jar
lwjgl-egl-javadoc.jar
lwjgl-egl-sources.jar
lwjgl-glfw.jar
lwjgl-glfw-javadoc.jar
lwjgl-glfw-natives-windows.jar
lwjgl-glfw-sources.jar
lwjgl-javadoc.jar
lwjgl-jawt.jar
lwjgl-jawt-javadoc.jar
lwjgl-jawt-sources.jar
lwjgl-jemalloc.jar
lwjgl-jemalloc-javadoc.jar
lwjgl-jemalloc-natives-windows.jar
lwjgl-jemalloc-sources.jar
lwjgl-libdivide.jar
lwjgl-libdivide-javadoc.jar
lwjgl-libdivide-natives-windows.jar
lwjgl-libdivide-sources.jar
lwjgl-llvm.jar
lwjgl-llvm-javadoc.jar
lwjgl-llvm-natives-windows.jar
lwjgl-llvm-sources.jar
lwjgl-lmdb.jar
lwjgl-lmdb-javadoc.jar
lwjgl-lmdb-natives-windows.jar
lwjgl-lmdb-sources.jar
lwjgl-lz4.jar
lwjgl-lz4-javadoc.jar
lwjgl-lz4-natives-windows.jar
lwjgl-lz4-sources.jar
lwjgl-meow.jar
lwjgl-meow-javadoc.jar
lwjgl-meow-natives-windows.jar
lwjgl-meow-sources.jar
lwjgl-nanovg.jar
lwjgl-nanovg-javadoc.jar
lwjgl-nanovg-natives-windows.jar
lwjgl-nanovg-sources.jar
lwjgl-natives-windows.jar
lwjgl-nfd.jar
lwjgl-nfd-javadoc.jar
lwjgl-nfd-natives-windows.jar
lwjgl-nfd-sources.jar
lwjgl-nuklear.jar
lwjgl-nuklear-javadoc.jar
lwjgl-nuklear-natives-windows.jar
lwjgl-nuklear-sources.jar
lwjgl-odbc.jar
lwjgl-odbc-javadoc.jar
lwjgl-odbc-sources.jar
lwjgl-openal.jar
lwjgl-openal-javadoc.jar
lwjgl-openal-natives-windows.jar
lwjgl-openal-sources.jar
lwjgl-opencl.jar
lwjgl-opencl-javadoc.jar
lwjgl-opencl-sources.jar
lwjgl-opengl.jar
lwjgl-opengles.jar
lwjgl-opengles-javadoc.jar
lwjgl-opengles-natives-windows.jar
lwjgl-opengles-sources.jar
lwjgl-opengl-javadoc.jar
lwjgl-opengl-natives-windows.jar
lwjgl-opengl-sources.jar
lwjgl-openvr.jar
lwjgl-openvr-javadoc.jar
lwjgl-openvr-natives-windows.jar
lwjgl-openvr-sources.jar
lwjgl-opus.jar
lwjgl-opus-javadoc.jar
lwjgl-opus-natives-windows.jar
lwjgl-opus-sources.jar
lwjgl-ovr.jar
lwjgl-ovr-javadoc.jar
lwjgl-ovr-natives-windows.jar
lwjgl-ovr-sources.jar
lwjgl-par.jar
lwjgl-par-javadoc.jar
lwjgl-par-natives-windows.jar
lwjgl-par-sources.jar
lwjgl-remotery.jar
lwjgl-remotery-javadoc.jar
lwjgl-remotery-natives-windows.jar
lwjgl-remotery-sources.jar
lwjgl-rpmalloc.jar
lwjgl-rpmalloc-javadoc.jar
lwjgl-rpmalloc-natives-windows.jar
lwjgl-rpmalloc-sources.jar
lwjgl-shaderc.jar
lwjgl-shaderc-javadoc.jar
lwjgl-shaderc-natives-windows.jar
lwjgl-shaderc-sources.jar
lwjgl-sources.jar
lwjgl-sse.jar
lwjgl-sse-javadoc.jar
lwjgl-sse-natives-windows.jar
lwjgl-sse-sources.jar
lwjgl-stb.jar
lwjgl-stb-javadoc.jar
lwjgl-stb-natives-windows.jar
lwjgl-stb-sources.jar
lwjgl-tinyexr.jar
lwjgl-tinyexr-javadoc.jar
lwjgl-tinyexr-natives-windows.jar
lwjgl-tinyexr-sources.jar
lwjgl-tinyfd.jar
lwjgl-tinyfd-javadoc.jar
lwjgl-tinyfd-natives-windows.jar
lwjgl-tinyfd-sources.jar
lwjgl-tootle.jar
lwjgl-tootle-javadoc.jar
lwjgl-tootle-natives-windows.jar
lwjgl-tootle-sources.jar
lwjgl-vma.jar
lwjgl-vma-javadoc.jar
lwjgl-vma-natives-windows.jar
lwjgl-vma-sources.jar
lwjgl-vulkan.jar
lwjgl-vulkan-javadoc.jar
lwjgl-vulkan-sources.jar
lwjgl-xxhash.jar
lwjgl-xxhash-javadoc.jar
lwjgl-xxhash-natives-windows.jar
lwjgl-xxhash-sources.jar
lwjgl-yoga.jar
lwjgl-yoga-javadoc.jar
lwjgl-yoga-natives-windows.jar
lwjgl-yoga-sources.jar
lwjgl-zstd.jar
lwjgl-zstd-javadoc.jar
lwjgl-zstd-natives-windows.jar
lwjgl-zstd-sources.jar
You are trying to compile LWJGL 2 code here. All the imports that it cannot find pertain to the verison 2 of LWJGL. The current version that you can get from the mentioned lwjgl site is 3 and version 3 is incompatible with version 2.
Either explicitly download LWJGL 2 from e.g. http://legacy.lwjgl.org/ or rewrite your code to work with LWJGL 3.
If you go the LWJGL 2 route, though, please note that it hasn't been actively maintained anymore for more than 6 years now.