The lower orders are anything that are less competant, or less developed in a particular context and a given set of parameters by which to judge rank.
For example, within the context of IQ, with the parameter of a high IQ being positively correlated with rank, then a man with an IQ of 140 would rank above a man with an IQ of 90. Thus the man with the IQ of 90 would be in the lower order whilst the man with the IQ of 140 would be in the higher order.
Another example could be alcohol content, with the paramter of higher percentage of alcohol per unit of mass the criterion for rank. A litre bottle of vodka would have a higher alchohol content than a latex tree, thus the latex tree would be in the lower order, and the vodka would be in the higher order.
Orders apply to all things depending on the context, the framework by which the things are being ranked. In one instance an item could be above another in rank, yet when judged by another set of criterion (another context) it could be lower in rank than the same object. For example, though a bottle of vodka has more alcohol per unit of mass than a latex tree, the latex tree may be able to yield more alcohol should its cellulose be converted into wood chips and then ethanol which wouild make it rank higher than the vodka.
Overall, when speaking of the lower orders, the term is used to refer to those things that are less capable than others in the context of the principle intention: that is to be willful and creative, and give rise to amd facilitate things that are willful and creative. Thus an able bodied man would be ranked higher than an asteroid, as the latter his less capacity for willful creation than a man, even though it can provide facility for creative expression (think of iron ore that are sourced from meterorites which can be used by men to make iron tools).